High-purity molybdenum dichloride dioxide and its manufacturing method

Abstract

The present invention relates to high-purity molybdenum dichloride dioxide and a method for producing the same. The molybdenum dichloride dioxide is characterized in that the silicon (Si) content among impurities is 400 weight ppm or less, and high-purity molybdenum dichloride dioxide can be obtained by producing the molybdenum dichloride dioxide through a sublimation purification process.

Description

[Technical Field]

[0001] The present invention relates to high-purity molybdenum dichloride dioxide (MoO2Cl2) and a method for producing the same, and more particularly to high-purity molybdenum dichloride dioxide suitable for use as a precursor for forming thin films by removing impurities that increase resistivity, and a method for producing the same. [Background technology]

[0002] Molybdenum dioxide dichloride (MoO2Cl2), which is used as a precursor for forming molybdenum-containing thin films, must be produced as a highly pure compound in order to form high-quality thin films.

[0003] Such high purity molybdenum dichloride dioxide is known in the prior art, such as Korean Patent Publication No. 10-2368870 and Korean Patent Publication No. 10-2020-0127226.

[0004] High-purity molybdenum oxychloride is disclosed in Korean Patent Publication No. 10-2020-0127226, and high-purity molybdenum oxychloride is disclosed in Korean Patent Publication No. 10-2368870, which mentions molybdenum dioxide dichloride as an example of the molybdenum oxychloride. Furthermore, high-purity molybdenum oxychloride is disclosed in International Patent Publication No. 2021-171742.

[0005] In the prior art, the purity of a compound is confirmed by analyzing the contents of Be, Mg, Al, Ga, Ge, As, Sr, Ba, W, Ti, U, Ag, Na, Co, Fe, In, Mn, Ni, Pb, Zn, Cu, Cr, Tl, Li, Th, Sc, Se, Hf, Ta, and Bi by ICP-MS, and by analyzing the content of K by AAS, and then calculating the purity from the resulting values.

[0006] Based on the above prior art, the applicant has studied the performance of molybdenum dichloride dioxide as a precursor for forming a thin film, and has found that among various impurities, there are impurities such as silicon (Si) that are not mentioned in the prior art. In particular, it has been found that silicon, when present at a certain level or above, increases the resistivity of the formed thin film, causing problems in the process of forming a high-quality molybdenum-containing thin film.

[0007] Therefore, it has been found that it is advantageous to form a high-quality molybdenum-containing thin film only by using high-purity molybdenum dichloride dioxide, from which impurities that can cause problems when used as a precursor for forming a thin film have been removed. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been devised in consideration of the above-mentioned conventional techniques, and its object is to provide highly purified molybdenum dioxide dichloride (MoO2Cl2) by reducing the content of impurities that deteriorate the properties of thin films, and a method for producing the same. [Means for solving the problem]

[0009] To achieve the above object, the molybdenum dichloride dioxide of the present invention is characterized in that the silicon (Si) content in impurities is 400 ppm by weight or less.

[0010] In this case, the impurities may contain silicon (Si) at a content of 99% by weight or more.

[0011] In one embodiment, the impurities may have a content of impurity elements other than silicon (Si) of less than 2 ppm by weight, and in another embodiment, the impurities may have a content of impurity elements other than silicon (Si) of less than 0.1 ppm by weight.

[0012] The impurities may also be silicon (Si), silver (Ag), aluminum (Al), arsenic (As), gold (Au), barium (Ba), calcium (Ca), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), potassium (K), lithium (Li), magnesium (Mg), manganese (Mn), sodium (Na), nickel (Ni), lead (Pb), antimony (Sb), tin (Sn), titanium (Ti), vanadium (V), tungsten (W), zinc (Zn), and zirconium (Zr).

[0013] In one embodiment, the molybdenum dichloride dioxide may have a hydrate content of less than 1.5 wt %, and in another embodiment, the hydrate content may be less than 1 wt %.

[0014] The high-purity molybdenum dichloride dioxide can be produced by a process including sublimation purification of molybdenum dichloride dioxide. [Effects of the Invention]

[0015] The molybdenum dichloride dioxide according to the present invention is highly purified and exhibits the effect of reducing the content of impurities that degrade the properties of the thin film formed when used as a precursor in the thin film formation process. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention will now be described in more detail. The terms and phrases used in the specification and claims should not be construed as being limited to their ordinary or dictionary meanings, but should be construed as meanings and concepts that correspond to the technical ideas of the present invention, based on the principle that the inventor can appropriately define the concepts of terms in order to best describe his / her invention.

[0017] Molybdenum dioxide dichloride (MoO2Cl2) generally contains trace amounts of impurities such as silicon (Si), silver (Ag), aluminum (Al), arsenic (As), gold (Au), barium (Ba), calcium (Ca), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), potassium (K), lithium (Li), magnesium (Mg), manganese (Mn), sodium (Na), nickel (Ni), lead (Pb), antimony (Sb), tin (Sn), titanium (Ti), vanadium (V), tungsten (W), zinc (Zn), and zirconium (Zr). Furthermore, it is highly hygroscopic, absorbing moisture from the air to form hydrates.

[0018] When using the molybdenum dichloride dioxide as a precursor for the thin film forming process, it is important not only to reduce the moisture content of the raw material itself but also to prevent contact with air during the process.

[0019] Even if the moisture problem is solved, another problem can occur during the thin film formation process, namely, the degradation of thin film properties due to the presence of impurities. To solve this problem, the prior art has used high-purity molybdenum oxychloride compounds.

[0020] However, when molybdenum dioxide chloride, which is one of the molybdenum oxychloride compounds, is used in an actual process, it has been found that the resistivity of the thin film increases. This is due to the influence of silicon (Si) contained in the molybdenum dioxide chloride.

[0021] Therefore, in the present invention, the problem of the deterioration of thin film properties is solved by using molybdenum dichloride dioxide having a silicon content of 400 weight ppm or less as a precursor for forming a thin film. It has been found that the problem of increased resistivity of the thin film formed when the silicon content of the impurities is 400 weight ppm or less can be solved, and a high-quality molybdenum-containing thin film can be formed.

[0022] The content of the impurities can be defined as the value obtained by subtracting the total content of elements measured at levels above the detection limit, which is taken as 100 wt%. Specifically, the silicon content can be measured using inductively coupled plasma spectroscopy (ICP-OES), and the other impurity components excluding silicon can be measured using inductively coupled plasma mass spectroscopy (ICP-MS). The values ​​calculated using these measurement methods are used to determine the purity of the molybdenum dichloride dioxide.

[0023] The molybdenum dichloride dioxide can be produced by reacting sodium molybdate (Na2MoO4) with thionyl chloride (SOCl2).

[0024] Specifically, sodium molybdate and thionyl chloride are reacted in a single step, and the reaction is carried out at room temperature under reflux conditions, allowing high-purity molybdenum dichloride to be obtained without side reactions.

[0025] In this synthesis method, sodium molybdate reacts with thionyl chloride to form NaMoO4-SOCl, and then molybdenum oxychloride sodium salt (NaMoO3Cl) is formed as an intermediate while SO2 is removed. When the molybdenum oxychloride sodium salt reacts with thionyl chloride again, molybdenum dioxide dichloride (MoO2Cl2) is produced via MoO3Cl-SOCl.

[0026] The reaction can be carried out in the presence of a reaction solvent. 10 Linear, branched or cyclic saturated or unsaturated hydrocarbons, halogenated alkyl (RH a X (4-a) (X=Cl, Br, or I)) can be used. The hydrocarbon can be hexane, cyclohexane, octane, or decane, and the alkyl halide can be dichloromethane, chloroform, or carbon tetrachloride.

[0027] Molybdenum dichloride dioxide can also be obtained in a two-stage synthesis method in which molybdenum tetrachloride oxide (MoOCl4) is synthesized and then used as a raw material to synthesize molybdenum dichloride dioxide (MoO2Cl2).

[0028] In the first step of the reaction, molybdenum oxide (MoO3) is used as a raw material. After reacting the molybdenum oxide with thionyl chloride (SOCl2), unreacted components are removed and molybdenum oxide tetrachloride is obtained by sublimation purification. Next, in the second step, the molybdenum oxide tetrachloride is mixed with a reaction solvent, and hexamethyldisiloxane (HMDSO) is added dropwise. After the reaction, the mixture is filtered and washed to obtain molybdenum dioxide dichloride.

[0029] High purity molybdenum dichloride dioxide is obtained by a step of sublimation purification of the molybdenum dichloride dioxide obtained by the above synthesis method.

[0030] The sublimation purification step can be carried out by charging molybdenum dichloride dioxide into a sublimation purification machine, heating it to a temperature at which the raw material sublimes, sublimating it, and then re-aggregating it.

[0031] The effects of the present invention will be explained below with reference to examples.

[0032] [Synthesis Example 1] MoOCl4 was synthesized in a one-step reaction.

[0033] MoO3 was placed in a reaction vessel and purged with N2 gas. Next, 5 equivalents of SOCl2 were added and heated to reflux to react. As the reaction progressed, the reaction solution in a suspension state turned reddish-black and all of the MoO3 was consumed. After 8 hours, the reaction was terminated and cooled to room temperature. The reaction solution was then filtered to remove unreacted MoO3, and the filtrate was concentrated under reduced pressure to remove the remaining SOCl2. Once the concentration under reduced pressure was complete, a dark green solid (MoOCl4 crude) was obtained. The MoOCl4 obtained above was purified by sublimation to obtain high-purity MoOCl4.

[0034] Next, MoO2Cl2 was synthesized in a two-step reaction.

[0035] MoOCl4 was charged into a reaction vessel and purged with N2 gas. 7 vol% DCM, the reaction solvent, was added and stirred at room temperature. After the solution turned dark red, 1 equivalent of HMDSO was slowly added dropwise. As HMDSO was added dropwise, a brown solid slowly formed, and upon completion of the addition, the solution turned into a brown suspension. The reaction was allowed to proceed at room temperature for 12 hours. After the reaction was complete, the solid was filtered and washed with DCM, the reaction solvent, until the filtrate was clear. The filtered solid was dried under vacuum to obtain MoO2Cl2 crude.

[0036] [Synthesis Example 2] Na2MoO4 was placed in a reaction vessel and purged with N2 gas. 2 equivalents of SOCl2 and 7.5 vol% DCM were added and heated to reflux to react. After 6 hours of reaction, the reaction was stopped and cooled to room temperature. The resulting solid was filtered and washed with DCM, the reaction solvent, until the filtrate was clear. The filtered and washed solid was dried under vacuum to obtain MoO2Cl2 crude.

[0037] [Example 1] The MoO2Cl2 obtained in Synthesis Example 1 was purified by sublimation using a sublimation purifier under the following conditions.

[0038] MoO2Cl2 was stored in a raw material storage container of the sublimation purification machine, and the heating temperature was maintained at 151°C, at which the raw material steadily sublimated. In this state, sublimated and re-aggregated MoO2Cl2 was deposited on the recovery section of the sublimation purification machine. During this re-aggregation process, the temperature of the recovery section was maintained at 50°C, and the vacuum level was maintained at 6.5 Torr.

[0039] [Example 2] The MoO2Cl2 obtained in Synthesis Example 2 was purified by sublimation using a sublimation purifier under the following conditions.

[0040] MoO2Cl2 was stored in a raw material storage container of the sublimation purification machine, and the heating temperature was maintained at 151°C, at which the raw material stably sublimated. In this state, sublimated and re-aggregated MoO2Cl2 was precipitated on the recovery side of the sublimation purification machine. The temperature of the re-aggregated recovery section was kept at 50°C, and the vacuum level was maintained at 6.5 Torr.

[0041] [Example 3] The MoO2Cl2 obtained in Example 2 was purified by sublimation using a sublimation purifier under the following conditions.

[0042] MoO2Cl2 was stored in a raw material storage container of the sublimation purification machine, and the heating temperature was maintained at 151°C, at which the raw material stably sublimated. By maintaining this condition, MoO2Cl2 sublimated and re-aggregated on the recovery side of the sublimation purification machine. The temperature of the re-aggregated recovery section was kept at 50°C, and the vacuum level was maintained at 6.5 Torr.

[0043] [Impurity content analysis] The impurity contents of the molybdenum dichloride dioxide obtained in Synthesis Examples 1 and 2 and Examples 1 to 3 were analyzed. The silicon content in the impurities was analyzed using ICP-OES, and the contents of the remaining impurity components excluding silicon were analyzed using ICP-MS. The results are shown in Table 1. In Table 1, the silicon content is expressed in ppm, and the contents of the remaining impurities are expressed in ppb.

[0044] [Table 1]

[0045] The results in Table 1 show that silicon accounts for a large proportion of the impurities contained in MoO2Cl2. In addition, the relatively high content of sodium among the impurities other than silicon is due to the production of NaCl as a by-product during the synthesis process.

[0046] In addition, the quantitative analysis results of the MoO2Cl2 and hydrate contents from the XRD analysis results are shown in Table 2. The quantitative analysis is a relative value calculated from the peak area, and all units are in weight %.

[0047] [Table 2]

[0048] The analysis results in Tables 1 and 2 confirm that the molybdenum dichloride dioxides of Examples 1 to 3 are high-purity compounds with low silicon content, with silicon (Si) content among impurities being 400 ppm by weight or less. In addition, the hydrate content was 1.5% by weight or less, confirming that the molybdenum dichloride dioxides are high-purity compounds with almost no hydrate content.

[0049] Although the present invention has been described above with reference to preferred embodiments, it is not limited to the above embodiments, and various modifications and alterations can be made by those skilled in the art without departing from the spirit of the present invention. It should be understood that such modifications and alterations fall within the scope of the present invention and the appended claims.

Claims

1. High-purity molybdenum dichloride dioxide, characterized in that the content of silicon (Si) among impurities is 400 ppm by weight or less.

2. 2. The high-purity molybdenum dichloride dioxide according to claim 1, wherein the impurities contain silicon (Si) in an amount of 99% by weight or more.

3. 2. The high-purity molybdenum dichloride dioxide according to claim 1, wherein the content of the remaining impurities, excluding silicon (Si), is less than 2 ppm by weight.

4. 2. The high-purity molybdenum dichloride dioxide according to claim 1, wherein the content of the remaining impurities, excluding silicon (Si), is less than 0.1 ppm by weight.

5. 2. The high-purity molybdenum dichloride dioxide according to claim 1, wherein the impurities are silicon (Si), silver (Ag), aluminum (Al), arsenic (As), gold (Au), barium (Ba), calcium (Ca), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), potassium (K), lithium (Li), magnesium (Mg), manganese (Mn), sodium (Na), nickel (Ni), lead (Pb), antimony (Sb), tin (Sn), titanium (Ti), vanadium (V), tungsten (W), zinc (Zn), and zirconium (Zr).

6. 2. The high-purity molybdenum dichloride dioxide of claim 1, wherein the molybdenum dichloride dioxide has a hydrate content of less than 1.5 wt. %.

7. 2. The high-purity molybdenum dichloride dioxide of claim 1, wherein the molybdenum dichloride dioxide has a hydrate content of less than 1% by weight.

8. A method for producing high-purity molybdenum dichloride dioxide, comprising a step of purifying molybdenum dichloride dioxide by sublimation.

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